The present invention relates to a recording and reproducing information apparatus such as a 8-mm VTR which can record and reproduce a video signal and a PCM audio signal at the same time, and more particularly to the recording and reproducing information apparatus for a PCM audio signal capable of selecting the audio data signal as desired, such that the PCM audio data or a different kind of digital data can be selectively recorded on a recording part for the PCM audio signal.
Consider that the PCM audio signal to be recorded concurrently with the video signal is not sampled by a sampling frequency being asynchronous to a field frequency of the video signal. If a constant ratio is not kept between the field frequency and the sampling frequency, in general, there may take place a disadvantage that the PCM audio cannot be recorded exactly.
The prior art described in JP-A-62-170078 is provided for overcoming the disadvantage of the VTR for recording and reproducing the video signal and the PCM audio signal at the same time. In this prior art, the number of samples to be recorded per field may be changed depending on the ratio of the field frequency of a video signal to the sampling frequency of an audio signal, for the purpose of maintaining the asynchronism between both of the frequencies.
This prior art, therefore, makes it possible to record and reproduce the video signal and the PCM audio signal sampled by the sampling frequency being asynchronous to the field frequency of the video signal. For example, it is possible to directly record the PCM audio signal sampled by the sampling frequency of 48 kHz or 32 kHz while recording the video signal sent from a broadcasting satellite.
Basically, the prior art enables to record normal digital data on the recording part in place of the PCM audio signal. For example, a still picture may be recorded and reproduced together with a moving picture. For the purpose, no additional processing circuit is required for the other kind of data only if the signal recorded on the recording medium keeps its format unchanged.
However, the technique for maintaining the asynchronism described in the prior art changes the number of data pieces to be recorded per field and the number of fields at which a predetermined amount of data is recorded and reproduced. Moreover, since the field head data remains undefined, the difficulty takes place in formatting the data at each field. If, on the other hand, the number of data pieces to be recorded per field is defined, the asynchronism disables to exactly record the input digital data.